Passivation of a homogeneous hydrogenation catalyst for the production of ethylene glycol

Abstract

A process for making ethylene glycol by feeding reactants including 1,2-dioxygenated organic compounds, an organometallic homogeneous catalyst, and hydrogen to a hydrogenation reactor, reacting at least a portion of the reactants with hydrogen in the presence of the organometallic homogeneous catalyst to produce a reaction product mixture containing ethylene glycol, and passivating the catalyst by contacting the catalyst with a carbon monoxide to thereby suppress the formation of by-product diols other that the ethylene glycol primary product, and suppress the formation of by-product tetrols and by-product glycolaldehyde acetals; and separating at least a portion of the ethylene glycol from the reaction product mixture.

What we claim is: 
     
       1. A process for making ethylene glycol comprising:
 (i) feeding reactants comprising 1,2-dioxygenated organic compounds, an organometallic homogeneous catalyst, and hydrogen to a hydrogenation reactor; 
 (ii) conducting a hydrogenation reaction by reacting at least a portion of the reactants with hydrogen in the hydrogenation reactor and in the presence of the catalyst to produce a reaction product mixture comprising ethylene glycol and the catalyst; 
 (iii) contacting the catalyst with a carbon monoxide gas composition containing at least 1 mole % carbon monoxide; and 
 (iv) separating at least a portion of the ethylene glycol from the reaction product mixture. 
 
     
     
       2. The process of  claim 1 , wherein said reaction product mixture contains at least 70 wt. % ethylene glycol. 
     
     
       3. The process of  claim 2 , wherein said reaction product mixture contains at least 90 wt. % ethylene glycol. 
     
     
       4. The process of  claim 2 , wherein the carbon monoxide composition comprises at least 50 mole % carbon monoxide. 
     
     
       5. The process of  claim 4 , wherein the carbon monoxide composition comprises at least 90 mole % carbon monoxide. 
     
     
       6. The process of  claim 1 , comprising contacting the reaction product mixture with the carbon monoxide gas composition under a carbon monoxide partial pressure of at least 0.01 bara. 
     
     
       7. The process of  claim 6 , wherein the partial pressure of carbon monoxide contacting the reaction product mixture is at least 10 bara. 
     
     
       8. The process of  claim 7 , wherein the carbon monoxide partial pressure pressure is at least 50 bara. 
     
     
       9. The process of  claim 8 , wherein the temperature of the reaction product mixture that is in contact with carbon monoxide gas composition is at least 100° C. 
     
     
       10. The process of  claim 8 , wherein the temperature of the reaction product mixture that is in contact with carbon monoxide composition is at least 225° C. 
     
     
       11. The process of  claim 8 , wherein the temperature of the reaction product mixture that is in contact with carbon monoxide gas composition is near or above the lowest operating temperature of liquid in the base of a distillation apparatus effective to separate from the liquid reaction product mixture at least 50 wt. % of ethylene glycol as a vapor that is present in the liquid reaction product mixture prior to entering the distillation apparatus. 
     
     
       12. The process of  claim 1 , wherein the residence time of carbon monoxide with the reaction product mixture is effective to reducing the rate of by-product diol formation. 
     
     
       13. The process of  claim 12 , wherein the residence time of carbon monoxide with the reaction product mixture is 10 minutes or less. 
     
     
       14. The process of  claim 1 , wherein the (iii) separation is conducted in a distillation apparatus comprising a fractional distillation column and taking ethylene glycol as an overhead distillate. 
     
     
       15. The process of  claim 1 , wherein the carbon monoxide composition is fed into the base of the distillation apparatus. 
     
     
       16. The process of  claim 1 , wherein the carbon monoxide composition is contacted with the reaction product mixture after the hydrogenation reaction is discontinued or to the reaction product mixture discharged from the hydrogenation reactor and before the reaction product mixture is introduced into an apparatus for conducting the (iii) separation. 
     
     
       17. The process of  claim 1 , wherein the process is continuous. 
     
     
       18. The process of  claim 1 , wherein the homogeneous organometallic catalyst comprises ruthenium atoms and a tridentate phosphorous ligand. 
     
     
       19. The process of  claim 1 , wherein the reaction product mixture is contacted with said carbon monoxide gas composition, and the cumulative supplemental amount of 1,2-propanediol and 1,2-butanediol formed as diol by-products after first contact with said carbon monoxide gas composition is less than 0.01 mole % based on the weight of the reaction product mixture. 
     
     
       20. The process of  claim 19 , wherein the supplemental cumulative amount of 1,2-propanediol and 1,2-butanediol is less than 0.003 mole %. 
     
     
       21. The process of  claim 1 , wherein the reaction product mixture is contacted with said carbon monoxide gas composition, and the cumulative supplemental amount of by-product tetrols formed as by-product tetrols after first contact with said carbon monoxide gas composition is less than 0.01 mole % based on the weight of the reaction product mixture. 
     
     
       22. The process of  claim 1 , wherein the cumulative supplemental amount of tetrols formed as tetrols by-products after first contact with said carbon monoxide gas composition is less than 0.005 mole % based on the weight of the reaction product mixture. 
     
     
       23. The process of  claim 1 , wherein the reaction product mixture is contacted with said carbon monoxide gas composition, and the cumulative supplemental amount of glycolaldehyde acetal compounds formed as acetal by-products after first contact with said carbon monoxide gas composition is less than 0.01 mole % based on the weight of the reaction product mixture.